Rajan,
Molecular seal:
- Not proper in cold environment because is capable to collect liquids following which there would be the risk of freezing and blockage
- Provide greater reduction in required purge gas
- Considerable large (higher structural and wind loads) and more expensive
Velocity seal:
- Proper in cold environment because doesn't collect liquid
- Provide lower reduction in required purge gas
- Smaller size and less expensive
Water seal at the stack bottom isn't a must and can be replaced by proper seal along with the required purge gas adjustment
Edited by fallah, 05 September 2016 - 03:44 AM.